This invention relates to a ground handling system for an airship.
The invention particularly concerns a ground handling system intended to facilitate fleet operation of passenger or cargo airships from a restricted terminal space while minimising the turn-around time.
The movement by airship of passenger streams between transport terminals, for example, near city centres or at airports involves various system requirements which include:
(i) that the airship should be of the minimum size necessary to sustain an optimum combination of fleet size and flight frequency for a given route in peak traffic density, and to operate as an economic single unit in alternative roles;
(ii) that the ground handling installation should permit operation of the airship from a limited base area, with due regard to local noise and height requirements, over an economically acceptable range of weather conditions; and
(iii) that the turn-round time in peak operation should be kept to a minimum.
Current proposals operating "heavy" helium-filled airships include two basic techniques:
(a) dynamic operation from a runway similar to aeroplane take off and landing. This method requires considerable space, and time is lost in backtracking to the take-off point. Operation in turbulence is however helped by the availability, through considerable forward speed, of adequate aerodynamic control throughout the approach and climb-out phases;
(b) vertical or near-vertical approach and climb-out using vectored thrust. This dramatically reduces the base area requirement, but position control on vertical thrust is difficult in rough conditions, particularly when the mean wind speed is low, due to the ineffectiveness of the control services. The vectored thrust installation also represents additional weight and cost.
In both cases, the time taken to load and unload passengers is a significant factor in the turn-round time, especially where the lack of ballast or hold-down facilities requires a "one-in, one-out" sequence.
The present invention provides a swivelling landing platform. The platform can be aligned to suit the wind direction, and incorporates arrester and accelerator systems such that the air speed of the air ship on approach and climb-out can be maintained at a sufficient magnitude both to ensure positive aerodynamic control and to sustain dynamically a reasonable under-capacity load without the use of vectored thrust. The platform further embodies a module handling system for the exchange of loaded passenger modules, so that the turn-round time may be considerably reduced.